Field of the Invention
The present invention relates to a method for producing a polybenzoxazole resin.
Polybenzoxazole resins are excellent in heat resistance, mechanical strength, insulation properties, dimensional stability, and the like, and therefore, they are widely used as not only fibers and films but also insulating materials or protective materials in electric or electronic parts, such as various devices or electronic substrates, e.g., multilayer wiring boards.
Related Art
In general, polybenzoxazole resins are formed by heat treating a precursor polymer which is obtained by polymerizing an aromatic diaminediol having an amino group and a hydroxyl group on carbon atoms adjacent to each other in an aromatic ring with a dialdehyde compound or a dicarbonyl compound, such as a dicarboxylic acid dihalide, in an organic solvent, such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), and dimethylformamide (DMF), at a high temperature of about 300° C.
As specific examples of polybenzoxazole resins produced by such a method, there are known polybenzoxazole resins formed by heat treating a solution of a precursor polymer which is obtained by allowing an aromatic diaminediol having an amino group and a hydroxyl group on carbon atoms adjacent to each other in an aromatic ring to react with a di(4-formylphenyl)alkane or a di(4-halocarbonylphenyl)alkane in dimethylformamide, while increasing the temperature from 200° C. and finally up to 300° C. (see Patent Document 1).
[Patent Document 1] WO 2012/137840